I predicted this a year or so ago (when I first heard of TOR), but as predictions go, they don't have value if they aren't published. Now there are issues in the news about how TOR doesn't provide the security that users expected.
The following is a picture from the EFF's website depicting how TOR supposedly provides anonymity for users' web browsing:
Just like perpetual motion is impossible, so is this idea of anonymity. In simplest terms, it comes down to understanding how trust works. A TOR user trusts (an action) the TOR client on her computer which trusts the TOR nodes to properly route her data without breaching confidentiality. The important little detail that is so often overlooked is that these TOR nodes are operated by ... that's right ... people. And people will ruin a security model every time, either deliberately (malice) or accidentally (ignorance). [Hanlon's Razor comes to mind: "Never attribute to malice that which can be adequately explained by stupidity."]
In the case of the embassy's pitfalls with TOR, users assumed (watch that!) that their traffic was not being monitored by the TOR network nodes, when in fact it was. This is not a pitfall of TOR's implementation, but of TOR's design. Since this is an anonymous network of nodes operated by people such that Adam does not know Eve, how can any user ever expect a trustworthy (not an action, but a state of assurance) network? Compare this to the "real world" ... would Jane expect that if she were to go to some special coffee shop and share her secrets with a total stranger that the secrets would stay safe with her? Regardless of whether Jane has that expectation, it would be prudent for you not to have that expectation yourself.
So, extrapolating upon this situation ... how long will it be until we have law enforcement regularly participating in TOR networks? The logical next step is either an arms race inside the TOR network or a total breakdown of the network altogether. Either we will see law enforcement participate and "security researchers" (terms used loosely) evaluating methods to evade untrustworthy--yet totally anonymous--TOR nodes, OR, we will see law enforcement agencies lobbying their respective governments to make TOR illegal. From where I sit, this looks like the former is the better option. And why not? After all, there are millions of ignorant people out there who will assume that total anonymity is actually possible-- actually achievable. But it's not. That's dictated by the physical laws of information security. And while they're out there using TOR, law enforcement has a new "beat to walk": the TOR networks.
Another perpetual motion attempt in InfoSec today is DRM which will be discussed in the future.